Decks, Patios, Porches and Docks - Tar paper over beam and joist

Hi, I am in the process of tearing down an old untreated :confused:pine deck built in the late 70's and rebuilding it with treated lumber. Underneath the decking, I noticed that both the joists and beams had a strip of tar paper along their full length. Considering that these untreated boards have been around for about 30 years, it appears that the tar paper has help preserve them. My question is, why isn't tar paper used today with treated joist and beams? I have been reading several books on decking and have been searching the web for any tip I can get, but have not read any reference to tar paper.

Thanks,
Vin

Whoever did yours back then did the best they could w/o treated lumber. Maybe they figured that was just as good, or they couldn't afford treated, or they just didn't believe it was any good.

I've seen somewhere (prob Holmes on Homes or similar) where they built one and used window and door flashing tape on the tops.

Heres a couple of sites that come up with a seach for "covering tops of deck joists".

Joist Jackets & Ledger Jackets - Deck Flashing (http://www.joistjackets.com/html/install.html)

http://www.graceathome.com/pages/downloads/TP_117.pdf

Thanks for the reply with links. Based on what I have read so far, I will be using some form of protection. My new deck will be built with treated lumber and composite decking. Hopefully, it will extend the life of the new deck so that I meet my maker before I have to do it again.

Again Thank you,
Vin
Beer 4U2

Whoever built that deck did as best they could at the time it was built, and the age of your old deck proves it. Today, we use Vycor (by Grace) instead of tar paper. It does the same thing -- protects the joist tops -- but, because of the way that it is designed, it seals around the screw shank as the screw is being driven and does a MUCH better job than the tar paper did. It will be the best $100 you ever spent on your deck, since it will basically double the life of the joists!